<header class="bar bar-nav">
    <h1 class='title'>下拉刷新</h1>
</header>
<!-- content应该拥有"pull-to-refresh-content"类,表示启用下拉刷新 -->
<div class="content pull-to-refresh-content" data-ptr-distance="55">
    <!-- 默认的下拉刷新层 -->
    <div class="pull-to-refresh-layer">
        <div class="preloader"></div>
        <div class="pull-to-refresh-arrow"></div>
    </div>
    <!-- 下面是正文 -->
    <div class="card-container">
        <div class="card">
            <div class="card-header">card</div>
            <div class="card-content">
                <div class="card-content-inner">
                    这里是第1个card，下拉刷新会出现第2个card。
                </div>
            </div>
        </div>
    </div>
</div>